Industrial Useful Field
This invention relates to a grinding wheel position detecting means for a surface grinding machine, in which a super-grain grinding wheel is composed of a base metal fastened to a longitudinal end portion of a rotating shaft and a super-grain layer provided on a longitudinal end face of said base metal, and a longitudinal end face of the super-grain layer is utilized as a grinding surface.
Prior Art
Generally, a change in a longitudinal position of grinding surface during grinding is caused by a wear of the grinding surface incurred by grinding work and an elongation of a rotating shaft due to thermal expansion, which produce changes in dimensions of workpiece.
If a position of a grinding surface of grinding wheel can be measured consecutively and finely in terms of such changes of dimensions of workpiece in an in-process manner, a control of dimensions of workpiece will become easy in association with a fine adjustment means of wheel shaft and a range of application of the grinding machine will be widened drastically.
For this reason, the following grinding wheel position detecting means have conventionally been developed.
(1) A means for detecting grinding wheel position, in which a touch probe of a measuring device is made touch to a grinding surface of grinding wheel and the position is detected by its movement. (Patent Publication No. 45-1392) PA0 (2) A means for detecting grinding wheel position, in which liquid or air is sprayed on a surface of grinding wheel and the position is detected by its pressure change. (Patent Publication (Kokai) No. 49-104290, Patent Publication No. (Kokai) 53-115993) PA0 (3) A means for directly measuring a wear of grinding surface of grinding wheel by a movement of an optical sensor such as a laser beam etc. (Patent Publication No. (Kokai) 55-128095)
However, since the grinding surface of grinding wheel is directly measured in all the foregoing conventional means, the following troubles have arisen.
In the means as described in the above article (1), the touch probe itself is worn out by the grinding surface of rotating grinding wheel so that a continuance of correct measurement is very difficult. Further, a large quantity of coolant or ground chips strike against the touch probe to cause a failure of correct measurement.
In the means as described in the above article (2), the air sprayed from a measuring nozzle is disturbed by coolant or ground chips so that a measuring error will be induced.
In the means as described in the above article (3), the laser beam will be disturbed or screened by coolant or ground chips. Further, it is necessary to install a very complicated and precise mechanism in a grinding field so that a cost-up will become inevitable.